This kind of high athletes are very active though even if they are not fighting. And by the looks of it, Crawford has the discipline that's why he reach this level of greatness. And so with Spence, when he fought Porter he was out for a long time, and then Ugas. But it didn't show any ring rust. So I don't think it will have a big effect if this two are not going to be active for at least a year like Crawford.
Yes, the physical trainings are intact even they are not fighting. Drills and exhibitions are always active for this
kind of title holder champ, they can't afford to relax and just do the preparation when the schedule is available, more on
their attitude and how they are doing extra activities to make sure that they are fit once the fight already has an exact date.
Champ always takes pride in defending their title.